Comparison
205/60 R16 vs 235/40 R18
Going from 205/60 R16 to 235/40 R18 steps up to a 18-inch rim while trimming sidewall to stay near OEM rolling diameter. This wheel and tire pairing barely shifts the rolling circumference. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement.
Dashboard speed shifts only marginally — within the noise of normal OEM tolerance. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 235/40 R18 is 7.2 mm shorter than 205/60 R16, shifting the speedometer by -1.10%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-7.2 mm
-1.10%
Speedometer at 100
98.9 km/h
-1.10% error
Ground clearance
-3.6 mm
ride height delta
Sidewall change
-29.0 mm
revs/km: 493.4
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/compare/205-60-r16-vs-235-40-r18Detailed comparison
| Metric | 205/60 R16 | 235/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 652.4 mm | 645.2 mm | -7.2 mm (-1.10%) |
| Sidewall height | 123.0 mm | 94.0 mm | -29.0 mm |
| Circumference | 2.050 m | 2.027 m | -22.6 mm |
| Revs / km | 487.9 | 493.4 | +5.4 |
| Ground clearance | reference | -3.6 mm | -3.6 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.9 km/h | -1.10 km/h |
Verdict: excellent
Within ±3% — speedometer, ABS and traction control should behave normally.
Speedometer impact
At a true 100 km/h, your dashboard will read 98.9 km/h after switching to 235/40 R18 — a -1.10% offset. Use the speedometer error calculator to recheck for other indicated speeds, and the speedometer error guide for the full background.
Ground clearance change
The new tire's half-diameter changes ride height by -3.6 mm. Small differences are absorbed by suspension travel, but anything beyond ±10 mm can affect headlight aim, fender clearance and bump-stop margin. See the plus-sizing guide before committing.
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205/60 R16
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235/40 R18
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